1. Field of the Invention
The invention relates to a volume control pedal for musicians and more particularly relates to the pedal's circuitry as well as aspects of the mechanical construction in view of such circuitry.
2. Prior Art
Pedals for volume control are popular with performing musicians, whether vocalists or instrumentalists performing on, by way of non-limiting example, guitars, steel guitars, fiddles and so on. Volume control pedals are popular despite if a sound control engineer is involved. Musicians simply desire independent control of boosting or fading their performance at times when the feeling is there and in order to achieve certain effects.
Prior art volume control pedals have characteristically relied on potentiometers such as pulley-spun dial-type potentiometers for voltage control. It is an object of the invention to provide a distinctive alternative to potentiometers, dial- or plunger-type or otherwise, in a volume control pedal.
Eliminating potentiometers in favor of a better alternative is advantageous because the price of audio-quality potentiometers has increased dramatically over the years concurrently as quality has apparently gone down. Audio product manufacturers find that keeping an on-hand stock in sufficient quantities of a diverse assortment of different potentiometers of premium quality is an expensive investment. Every year the problem is exacerbated by rising costs, discontinued product lines, and the gradual cheapening of quality. In audio work, even slight changes in quality produce discernible problems in the final audio output.
Potentiometers are categorized according to many characteristics including what is sometimes known as taper. For instance there are potentiometers offered not only with linear or “audio” taper but also various logarithmic tapers. However the inventor hereof finds that the logarithmic-taper potentiometers he has experimented were undesirably inconsistent. Volume control pedals commonly use 500,00 ohm potentiometers made of hot molded carbon. The least imperfection causes problems that can be heard in the final audio output. Just as problematical, an audio equipment manufacturer can only obtain whichever taper profiles that potentiometer OEM's offer off-the-shelf unless the manufacturer is so large it can afford to order custom potentiometers. Regardless, the selection of potentiometers is fairly limited to a finite number of different products.
Since the 1960's the prior art has seen a series of “light beam” pedals, or pedals which used “light beam” circuits to control signal voltage. In the professional music world these light beam pedals had a sour reputation. There were at least three well-known problems with them:—they lost high-end frequency, they would often not go all the way OFF, and they didn't rock very comfortably underfoot.
The inventor hereof examined at least three varieties of these 1960's light beam pedals and discovered the following. The electronics inside all used a photo-resistor arrangement. These kinds of photo-resistors are sometimes called Cds cells. The light beam source in all instances was an incandescent light. The control over light intensity that shined on the photo-resistor was accomplished in one of three ways which in common shared the principle of the stroke of a shutter. The simplest way involved the simple eclipse of the light source by an opaque shutter. Full retraction of the shutter corresponded to full transmissivity of the light as full extension corresponded to full blockage, with varying degrees of transmissivity corresponding to intermediate positions accordingly. A second way used graduated material thickness in which a dark plastic wedge-shaped shutter's material thickness attenuated the light beam. That is, the thinner portions of the wedge corresponded to more transmissivity of the light beam as the thicker portions corresponded to more blockage. The third way had an opaque shutter that was formed with an elongated V-shaped slit. The width at the top of the V-shaped slit corresponded to maximum transmissivity of light as the vertex at the bottom of the V-shaped slit reached the point of full blockage.
The problems of the prior art light beam pedals were discovered to be arguably attributable to the following. As for loss of high end frequency, evidently the prior art light beam control circuits presented a music instrument having a magnetic pickup with a low-impedance output when the magnetic pickup needed to see a high impedance output in order to preserve the high end frequencies. The failure to go to full OFF appeared to be due to leakage of ambient light onto the photo-resistors. And the unnatural feel of the light beam foot pedals seemed to be caused by the absence of inherent drag as in dial-type potentiometers. Although there is no felt drag or friction between a shutter and light beam, the drag that the prior art light beam pedals introduced by way of springs still felt unnatural underfoot. In the absence of drag, the treadle was free to sink to full ON or OFF if the musician lifted his foot. However the drag that was introduced were simple spring arrangements which biased the treadle to a given “HOME” position nevertheless. The spring arrangements of the prior art failed to adequately balance the treadle in the position chosen for the moment by the musician (if he pulled his foot off). Moreover the springs could require a constant fight underfoot and did not shift and glide through or hold positions like pulley-spun dial-type potentiometer pedals.
These and other problems have plagued the prior art light beam pedals out of disfavor and virtual disuse, not all of which problems were likely discovered by the studies of the inventor hereof. What is needed is a solution which eliminates potentiometers in a volume control pedal without re-incorporating the problems associated with prior art light beam pedals.